Inhaler with breath actuated dose counter

ABSTRACT

A device is disclosed for dispensing a fluid supplied from an external fluid source. The device comprises a transducer adapted to receive a fluid from the fluid source, and a collapsible linkage coupling the transducer and the fluid source. The linkage has a collapsible joint inhibiting discharge of the fluid source when in a locked orientation. The device further comprises a movable member coupled to the linkage such that inhalation forces on the device cause the linkage to collapse thereby discharging the fluid from the fluid source. The device may further include a dose counter coupled to the fluid source for registering the amount of doses administered from the fluid source.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of copending application Ser. No. 10/888,445, filed on Jul. 9, 2004, incorporated herin by reference in its entirety, which claims priority from U.S. provisional application serial number 60/487,493, filed on Jul. 14, 2003, incorporated herein by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not Applicable

NOTICE OF MATERIAL SUBJECT TO COPYRIGHT PROTECTION

A portion of the material in this patent document is subject to copyright protection under the copyright laws of the United States and of other countries. The owner of the copyright rights has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the United States Patent and Trademark Office publicly available file or records, but otherwise reserves all copyright rights whatsoever. The copyright owner does not hereby waive any of its rights to have this patent document maintained in secrecy, including without limitation its rights pursuant to 37 C.F.R. § 1.14.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains generally to metered dose inhalers and more specifically, to a metered dose inhaler with a breath actuated delivery mechanism and dose counter.

2. Description of Related Art

Inhalers are commonly used to deliver a wide range of medicaments to the bronchial passages, lungs and bloodstream of the user. Typical inhalers hold a container of pressurized medicament and propellant that is actuatable, generally by compression, to deliver a dose of medicament through a mouthpiece to the patient.

It is generally desirable for the dose of medication to be dispensed at the same time that the patient inhales air to permit the majority of medication to enter the lung rather than the mouth or esophagus. A number of inhalers have been developed that use breath actuated devices to automatically initiate the discharge of the medicament from the container when the patient inhales. Many of these devices, such as U.S. Pat. No. 5,069,204 to Smith et al., use latching mechanisms that require a considerable amount of air pressure to release the medicament. These higher release pressures lead to difficulty of use, and discharge at non-optimal points in the patient's breath cycle.

It is therefore an object of the present invention to provide a breath-actuated inhaler having a controllable release mechanism that is sensitive to the inhalation forces of the user to provide synchronous air entrainment and medicament delivery. It is further an object of the present invention to provide a simple and reliable dose counter responsive to discharge of the medicament container.

BRIEF SUMMARY OF THE INVENTION

According to a first aspect of the invention, an apparatus is provided for dispensing a first fluid supplied from an external fluid source comprising a transducer adapted for receiving the first fluid from the fluid source, wherein translation of a portion of the fluid source along a first axis releases the first fluid into the transducer. The apparatus will generally have a loading member coupled to the fluid source to impose a biasing force to the fluid source along the first axis.

In all cases, the apparatus has a linkage coupling the transducer and the fluid source, the linkage having a collapsible joint inhibiting translation of the fluid source in the first axis when the collapsible joint is oriented in a first position, and allowing translation of the fluid source in the first axis when the collapsible joint is oriented in a second position. The apparatus further comprises a movable member coupled to the linkage, the moveable member responsive to an inhalation force exerted on the moveable member, the inhalation force causing the movable member to shift the collapsible joint from the first position to the second position, thereby allowing translation of a portion of the fluid source in the first axis from a stowed position to a discharge position to discharge the first fluid into the transducer.

In preferred embodiments, the transducer further comprises one or more vents to entrain the first fluid with a second fluid. Additionally, there may be a plug coupled to the transducer. Ideally, the plug is retained in a first chamber of the transducer and has a bluff surface such that the axis of the bluff surface is perpendicular to the first axis.

The apparatus of the present invention has an inhalation horn coupled to the transducer. The inhalation horn has a second chamber positioned along a second axis, wherein the second chamber is in communication with the first chamber via an outlet positioned at a first end of the second chamber. Suction on the inhalation horn by the user causes an inhalation force on the moveable member. In many embodiments, the second axis is perpendicular to the first axis. Generally, the second chamber has an internal cross section that increases from the first end to a second end forming an opening in the horn. In some embodiments, the internal cross section of the second chamber is parabolic.

Typically, the moveable member comprises a flap rotatably mounted to the transducer, wherein the flap rotates in response to the inhalation force. The flap is generally configured to rotate from a first orientation retaining the collapsible joint in the first position, to a second orientation allowing the collapsible joint to move to the second position as a result of the force applied in the first axis. Usually the device includes a flap spring coupled to the flap and the transducer to return the flap from the second orientation to the first orientation after the inhalation force has subsided.

In a preferred embodiment, the linkage comprises an upper link and a lower link, the upper link and the lower link rotatably attached to form the collapsible joint, a first end of the lower link rotatably housed in the transducer. A second end of the lower link is coupled to the flap and the mating surfaces of the lower link and the flap are configured so that the lower link contacts the flap to retain the collapsible joint in the first position when the flap is in the first orientation. When the flap is in the second orientation, the lower link is free to advance past the flap to allow the collapsible joint to move to the second position. In a preferred embodiment, a reset spring is coupled to the lower link to return the collapsible joint from the second position to the first position.

In some embodiments, a container holder is configured to receive a first end of the fluid source, wherein the container holder is coupled to the upper link. The container holder further comprises one or more protrusions.

Preferably, a dust cover is pivotably coupled to the transducer. The dust cover covers the horn opening in a first orientation, and allows access to the horn opening in a second orientation. In a preferred embodiment, the dust cover comprises one or more cams that are configured to contact the one or more protrusions on the container holder upon rotation of the dust cover from the second orientation to the first orientation, thereby advancing the container holder and fluid source from the discharge position to the stowed position.

In an alternative embodiment, the moveable member comprises a diaphragm mounted to the transducer, wherein a central portion of the diaphragm moves in response to the inhalation force. In this configuration, the collapsible joint is coupled to the central portion of the diaphragm, so that the inhalation force deflects the central portion of the diaphragm to orient the collapsible joint from the first position to the second position.

In another aspect of the invention, the apparatus comprises a dose counter coupled to the fluid source. Ideally, the dose counter is responsive to motion of the fluid source in the first axis to count each dose of fluid released from the fluid source.

In one embodiment, the dose counter further comprises a first wheel having a plurality of teeth along its perimeter, the plurality of teeth positioned to rotationally advance the first wheel in response to movement of the fluid source along the first axis. A second wheel positioned adjacent the first wheel, the second wheel having markings for indicating the number of doses discharged from the fluid source. The first wheel is preferably configured to engage the second wheel such that the second wheel rotates at a scaled movement in relation to the first wheel.

The apparatus may further comprise a sleeve configured to house a portion of the fluid source, wherein the sleeve has a protrusion that contacts the teeth of the first wheel to rotationally advance the first wheel as the fluid source is advanced in the first axis. The loading member may also have a spring coupled to the sleeve, wherein the spring provides a compressive force to the fluid source to bias the fluid source to move in the first axis.

In some embodiments, the apparatus may further have a manual release button. The button is coupled to the collapsible joint to manually shift the collapsible joint from the first position to the second position, thereby releasing the first fluid into the transducer.

In another aspect of the invention, an inhaler for dispensing metered doses of a medicament comprises a fluid source containing the medicament, wherein the fluid source has a cylindrical container having a nozzle located in line with a discharge axis of the container. The nozzle discharges the medicament when the container is advanced relative to the nozzle from a stowed position to a discharge position along the discharge axis. The inhaler further includes a transducer having a surface configured to engage the nozzle of the fluid source. The inhaler preferably has a loading member coupled to the container, the loading member imposing a biasing force to the container to discharge the container along the first axis. A linkage couples the transducer and the container, wherein the linkage has a collapsible joint inhibiting translation of the container in the first axis when the collapsible joint is oriented in a first position, and allowing translation of the container in the first axis when the collapsible joint is oriented in a second position. The inhaler also has a movable member coupled to the linkage, the moveable member responsive to an inhalation force, the inhalation force causing the movable member to shift the collapsible joint from the first position to the second position, thereby allowing translation of the container in the first axis from the stowed position to the discharge position to discharge the fluid into the transducer.

The moveable member comprises a flap rotatably mounted to the transducer, wherein the flap rotates in response to the inhalation force. The flap is configured to rotate from a first orientation retaining the collapsible joint in the first position, to a second orientation allowing the collapsible joint to move to the second position as a result of the force applied in the first axis.

The linkage preferably has an upper link and a lower link, the upper link and the lower link rotatably attached to form the collapsible joint, a first end of the lower link rotatably housed in the transducer. A container holder is configured to receive a first end of the container, wherein the container holder is coupled to the upper link. In some embodiments, the container holder further comprises one or more protrusions. A dust cover is pivotably coupled to the transducer, wherein the dust cover covers a horn opening in a first orientation, and allowing access to the horn opening in a second orientation. The dust cover may also have one or more cams configured to contact the one or more protrusions on the container holder. Upon rotation of the dust cover from the first orientation to the second orientation, the container holder and container are advanced from the stowed position to the discharge position.

In another aspect of the invention, a dose counter is coupled to the container, wherein the dose counter is responsive to motion of the container in the first axis to count each dose of fluid discharged from the fluid source. In one embodiment, the dose counter comprises a first wheel having a plurality of teeth along its perimeter, the plurality of teeth positioned to rotationally advance the first wheel in response to movement of the fluid source along the first axis, and a second wheel positioned adjacent the first wheel, the second wheel having markings for indicating the number of doses discharged from the fluid source. Preferably, the first wheel is configured to engage the second wheel such that the second wheel rotates at a scaled movement in relation to the first wheel.

In yet another aspect of the invention an inhaler for dispensing metered doses of a medicament comprises a fluid source containing the medicament. The fluid source has a nozzle and a container, wherein the nozzle discharges the medicament when the container is advanced relative to the nozzle from a stowed position to a discharge position along a first axis. The inhaler has a transducer having a surface configured to engage the nozzle of the fluid source and a loading member coupled to the container, the loading member imposing a force to the container to bias the container to discharge along the first axis.

The inhaler further has a means for collapsibly retaining the fluid source from translating along the first axis a means for releasably supporting the collapsible retaining means, wherein the releasable support means releases support of the collapsible retaining means in response to an inhalation force.

In many embodiments, the releasable support means has a first orientation retaining the collapsible retainer means in a first, locked position, and a second orientation allowing the retainer means to collapse to a second unlocked position, and wherein the inhalation force causes the releasable support means to shift from the first orientation to the second orientation, thereby allowing translation of the container in the first axis from the stowed position to the discharge position to discharge the fluid.

In another aspect of the invention, the inhaler also includes a means for counting the number of doses of dispensed medicament, wherein the counting means is responsive to the axial motion of the container. Preferably, the counting means is responsive to both the motion of the container from the stowed position to the discharged position, and the motion of the container from the discharged position back to the stowed position.

In many embodiments, the counting means comprises a gear means for translating the axial motion of the container into a corresponding radial motion, and a display means for displaying the number of doses based on the radial motion of the gear means. In preferred embodiments, the display means may be scaled with respect to the gear means to match the total dose count of the fluid source.

In yet another aspect of the invention, an inhaler for dispensing metered doses of a medicament comprises a fluid source comprising a cylindrical container having a nozzle located in line with a discharge axis of the container, wherein the nozzle discharges the medicament when the container is advanced relative to the nozzle along the discharge axis. A container sleeve is configured to house a portion of the container, the container sleeve having a protrusion extending outward radially from the container. The inhaler further comprises a first wheel having a plurality of teeth along its perimeter, the plurality of teeth positioned to rotationally advance the first wheel in response to contact from the protrusion on the container sleeve as the container sleeve and container advance in the discharge axis, wherein the rotation motion of the first wheel indicates the number of metered doses dispensed from the fluid source.

In a preferred embodiment, a second wheel is positioned adjacent the first wheel, the second wheel having markings for indicating the number of doses discharged from the fluid source, wherein the first wheel is configured to engage the second wheel such that the second wheel rotates at a scaled movement in relation to the first wheel. The first wheel has a plurality of engagement surfaces for engaging the second wheel, wherein the number of engagement surfaces varies the rate of the movement of the second wheel with respect to the first wheel.

In yet another aspect, an inhaler for dispensing metered doses of a medicament is disclosed. The inhaler has, or is designed to be used with a fluid source containing medicament. The fluid source has a container having a nozzle located in line with a discharge axis of the container, wherein the nozzle discharges the medicament when the container is advanced relative to the nozzle from a stowed position to a discharge position along the discharge axis.

The inhaler further comprises a housing having a surface configured to engage the nozzle of the fluid source, the surface adapted for receiving the fluid from the fluid source. A loading member is coupled to the container, wherein the loading member imposes a biasing force to the container in the stowed position to discharge the container along the first axis. A linkage couples the housing and the container, wherein the linkage has a collapsible joint connecting first and second links configured to restrain translation of the container in the first axis. The collapsible joint is restrained from moving by a restraining surface on a movable member.

The moveable member is responsive to an inhalation force causing the movable member to shift the restraining surface to release the collapsible joint, thereby allowing translation of the container in the first axis from the stowed position to the discharge position to discharge the fluid into the housing.

In one embodiment of the current aspect, the first link and second link each have first ends rotationally mounted with respect to the housing to form a loading path parallel to the first axis. The collapsible joint is located off-center from the loading path in the stowed position such that the collapsible joint is predisposed to collapse in absence of restraint from the moveable member.

In several embodiments, the moveable member comprises a flap rotatably mounted to the housing, wherein the flap rotates in response to the inhalation force to shift the restraining surface.

In one embodiment, the second member has a second end restrained by the restraining surface of the flap, and the flap is configured to rotate from a first orientation retaining the second end of the second member, to a second orientation releasing the second member from the restraining surface, thereby collapsing the collapsible joint as a result of the force applied in the first axis.

In an alternative embodiment, the second member has a second end restrained by a trip link rotationally coupled to the flap. The trip link having a catch restraining motion of the second end of the second link in the stowed position.

Preferably, the trip link has a contact surface mating with the restraining surface of the flap. The restraining surface is configured to inhibit rotation of the trip link with respect to the flap (when the flap is in a first orientation) to retain the second end of the second link in the catch. The flap is configured to rotate from the first orientation to a second orientation to allow the contact surface of the trip link to advance past the restraining surface of the flap, thereby allowing the trip link to rotate to release the second end of the second link from the catch.

In one embodiment, the inhaler further comprises a container holder configured to receive a first end of the container, wherein the container holder allows translation of the first end of the first link along the loading path to allow collapse of the collapsible knee when not restrained by the moveable member. The container holder may further comprises one or more protrusions, such that one or more cams of a dust cover pivotably coupled to the housing contact the one or more protrusions on the container holder upon rotation of the dust cover, thereby advancing the container holder and linkage from the discharge position to the stowed position. Preferably, the trip link is configured to engage the second end of the second link upon advancement of the container holder from the discharge position to the stowed position.

Another aspect is an apparatus for dispensing a fluid supplied from an external fluid source. The apparatus has a housing adapted for receiving the fluid from the fluid source, wherein translation of a portion of the fluid source from a stowed position to a discharge position along a first axis releases the first fluid into the housing. A loading member imposes a biasing force on the fluid source in the stowed position to discharge the fluid source along the first axis.

The apparatus further comprises a linkage coupling the housing and the fluid source, the linkage having a collapsible joint connecting first and second links configured to restrain translation of the fluid source in the first axis. The second link has a first end rotationally mounted with respect to the housing and a second end coupled to a restraining surface on a movable member. The moveable member may be a flap that is responsive to an inhalation force, the inhalation force causing the movable member to shift the restraining surface to release the collapsible joint, thereby allowing translation of the fluid source in the first axis from the stowed position to the discharge position to discharge the fluid into the housing.

In one embodiment, the second end of the second member is restrained by a trip link rotationally coupled to the flap, wherein the trip link has a catch restraining motion of the second end of the second link in the stowed position.

The trip link has a contact surface mating with the restraining surface of the flap, wherein the restraining surface is configured to inhibit rotation of the trip link with respect to the flap when the flap is in a first orientation to retain the second end of the second link in the catch. The flap is configured to rotate from a first orientation to a second orientation to allow the contact surface of the trip link to advance past the restraining surface of the flap, thereby allowing the trip link to rotate to release the second end of the second link from the catch.

The first link preferably has a first end rotationally mounted with respect to the housing such that the first ends of the first and second links form a loading path parallel to the first axis. In the stowed position, the collapsible joint is located off-center from the loading path to predispose collapse of the collapsible joint in absence of restraint from the moveable member.

A further aspect is an inhaler for dispensing metered doses of a medicament. The inhaler comprises a housing configured to house the translating portion of a fluid source. There are first and second angled contact surfaces coupled to the housing along with a rotational member that translates in the direction of the housing in the discharge axis. The first angled surface is disposed on the rotational member in opposition to the second angled surface such that motion of the housing upon discharge engages the first and second opposing angled surfaces to rotationally advance the rotation member with respect to the housing. A display wheel advances in response to motion from the rotation member to indicate the number of metered doses dispensed from the fluid source.

Preferably, the display wheel is scaled with respect to the motion of the rotation member. A planetary gear mechanism may be coupled to the rotational member to scale the motion of the display wheel to be a fraction of the motion of the rotational member.

In one embodiment, the first angled surface comprises one or more keys disposed on a perimeter of the rotating member. The second angled surface may comprise a plurality of tines disposed on the inside of a cover disposed around the housing such that the keys engage successive tines upon each discharge of the fluid source.

In addition, third and fourth angled contact surfaces may also be included. The third angled surface may be disposed on the rotational member in opposition to the fourth angled surface. The fourth angled surface is fixed from rotational motion so that motion of the housing upon recharge engages the third and fourth opposing angled surfaces, thereby further rotating the rotation member with respect to the housing.

Another aspect is a method for counting metered doses of medicament dispensed from a fluid source. The method includes the steps of advancing the fluid source in a first direction to dispense medicament, advancing a rotational member incrementally in response to motion from the fluid source, scaling the motion of the rotational member, and advancing a display wheel in response to the scaled motion of the rotational member to indicate the number of metered doses dispensed from the fluid source.

The method may further include the steps of advancing the fluid source in a second direction opposite said first direction to recharge the medicament, and advancing a rotational member incrementally in response to motion from the fluid source in the second direction.

A first angled surface on said rotational member may be engaged with a second angled surface that is fixed with respect to rotation to advance the rotational member in response to motion from the fluid source in the first direction. Furthermore, a third angled surface on said rotational member may be engaged with a fourth angled surface that is fixed with respect to rotation to advance the rotational member in response to motion from the fluid source in the second direction.

Further aspects of the invention will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing preferred embodiments of the invention without placing limitations thereon.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

The invention will be more fully understood by reference to the following drawings which are for illustrative purposes only:

FIG. 1A is an exploded view of the upper portion and dose counter of an embodiment of the present invention

FIG. 1B is an exploded view of the lower portion of the embodiment of FIG. 1A, including the release mechanism.

FIGS. 2A-C are perspective views of the exterior housing of the embodiment of the inhaler of FIGS. 1A-B in a fully assembled configuration.

FIG. 3A is a cross-sectional view detailing the release mechanism of the present invention in a stowed configuration.

FIG. 3B illustrates the device of FIG. 3A with the flap rotated as a result of inhalation forces.

FIG. 3C illustrates the device of FIG. 3A with the collapsible knee in a collapsed configuration and the fluid source discharged.

FIG. 3D illustrates the device of FIG. 3A with the flap returned to the stowed position and the collapsible knee still in a collapsed configuration.

FIG. 3E illustrates the device of FIG. 3A with the release mechanism returned to its stowed configuration.

FIG. 4A is a perspective view of an embodiment of the flap of the present invention.

FIG. 4B illustrates a cross-sectional schematic view the flap of FIG. 3A with the lower linkage retained by the flap in the stored configuration.

FIGS. 5A-B show schematic views of the flap and transducer of the present invention.

FIG. 6A is a perspective view of an embodiment of the transducer of the present invention.

FIG. 6B illustrates a cross-sectional schematic view the transducer of FIG. 6A with the fluid source in a stowed configuration.

FIG. 7A is a cross-sectional view detailing the release mechanism of the present invention in a stowed configuration and the dust cover cut out to show the release mechanism.

FIG. 7B illustrates the device of FIG. 7A with the dust cover rotated away from the horn and the release mechanism in the stowed configuration prior to breath actuation.

FIG. 7C illustrates the device of FIG. 7B with the release mechanism in the discharged configuration after breath actuation.

FIG. 7D illustrates the device of FIG. 7B with the cam of the dust cover driving the release mechanism back to the stowed configuration.

FIG. 8A is a cross-sectional view of the outer cover of the device to illustrate the dose counting mechanism of an embodiment of the present invention in a stowed configuration.

FIG. 8B illustrates the device of FIG. 8A with the container sleeve traveling part way through the discharge of the fluid source.

FIG. 8C illustrates the device of FIG. 8A with the container sleeve at the fully discharged configuration.

FIG. 8D illustrates the device of FIG. 8A with the container sleeve returning to the stowed position.

FIG. 9 is a schematic view of the container sleeve and biasing spring of the present invention.

FIG. 10 illustrates an embodiment of the dose counter wheel of the present invention.

FIGS. 11A-C illustrate an embodiment of the display wheel of the present invention.

FIGS. 12A-E are schematic views of the dose counter wheel and display wheel through various counting configurations.

FIG. 13 is a cross-sectional view of an alternative embodiment of the present invention having a release mechanism using a diaphragm.

FIG. 14 is a perspective view of an alternative embodiment of the present invention having a release mechanism above the fluid source.

FIG. 15 is an exploded view of the device of FIG. 14.

FIGS. 16A-D are schematic views of the device of FIG. 14 traveling trough its range of motion from the stowed position, to discharge position, back to the stowed position.

FIG. 17 illustrates the device of FIG. 14 having an electronic dose counter.

FIG. 18 is an alternative embodiment of the present invention with a portion of the outer cover removed to show the release mechanism and a mechanical dose counter with a vertically mounted display wheel.

FIGS. 19A-B illustrate the release mechanism of the device of FIG. 18.

FIGS. 20A-B illustrate the dose counter of the device of FIG. 18.

FIGS. 21A-F illustrate a further embodiment of the dose counter through one breath actuation cycle.

FIGS. 22A and B illustrate perspective views of the dose counter of FIGS. 21A-F.

FIG. 23 shows a top view of the dose counter of FIGS. 21A-F.

FIG. 24 A-D illustrates motion of a breath actuation mechanism using a trip link.

DETAILED DESCRIPTION OF THE INVENTION

Referring more specifically to the drawings, for illustrative purposes the present invention is embodied in the apparatus generally shown in FIG. 1A through FIG. 24D. It will be appreciated that the apparatus may vary as to configuration and as to details of the parts, and that the method may vary as to the specific steps and sequence, without departing from the basic concepts as disclosed herein.

Referring first to FIGS. 1A and 1B, an inhaler 20 of the present invention is shown in an exploded view with a breath actuation assembly 100 and a dose counter assembly 130. The breath actuation assembly 100 and the dose counter assembly 130 are housed along with medicament fluid source 22 inside front cover 42, back cover 44, and top cap 54, all preferably comprising medical grade plastic or other suitable materials known in the art. Fluid source 22 may comprise a conventional Metered Dose Inhaler (MDI) container or other propellant based medicament readily available in the art. Fluid source 22 generally comprises container 108 holding a mixture of medicament and propellant, and nozzle 110, which is in line with the discharge axis 86 of the container 108, as shown in FIG. 6B. When the container 108 is advanced relative to the nozzle 110 in the direction of the discharge axis 86 (i.e. the nozzle 110 is pushed into the container 108), the medicament is discharged out the nozzle 110 in the direction of the discharge axis 86.

Turning now to FIGS. 2A through 2C, inhaler 20 is shown in an assembled configuration with dust cover 40 pivotally mounted to cover inhalation horn 58. The dust cover 40 may be rotated away from horn 58 to expose opening 60, as shown in FIG. 2B. A manual release button 62, as shown in FIG. 2C, may also be incorporated into the back cover 44. Top cap 54 has an opening 56 to give visual access to display wheel 52.

Referring also to FIGS. 1B and 3A through 3E, the breath actuation assembly 100 comprises a housing or transducer 32 that rotatably houses lower link 28 at pivot 78. Lower link 28 is connected to upper link 26 at collapsible joint 66. Reference may also be made to FIGS. 5A-6B, wherein the transducer is illustrated in greater detail. Container holder 24 is shaped to receive the nozzle end of container 108 such that the nozzle 110 passes through to contact surface 112 of the transducer 32. Container holder 24 also has a pair of guides 122 having slots 90 sized to house a pair of bosses 92 as shown in FIG. 7A at the upper end of upper link 26.

As shown in FIGS. 3A through 4B, flap 34 is rotatably mounted to the transducer 32 via peg 98, which extends across the top surface of flap 34, and holes 114 in the sidewalls of transducer 32. The bottom and side extremities of flap 34 are sized to fit within the internal surface of transducer 32 to form gap 76. The flap 34 has an upper restraining surface 72 configured to retain arm 74 of lower link 28 when the flap is in its nominal position shown in FIG. 4B.

As illustrated in FIGS. 6A and 6B, the transducer 32 is configured to receive nozzle 110 of fluid source 22 at surface 112. The transducer also comprises an inlet 106 that spans from surface 112 to a first chamber 102. The inlet 106 is configured to be in line with the nozzle 110 and discharge axis 86 such that medicament discharged from the fluid source 22 is received through the inlet 106 and downstream into first chamber 102.

The transducer 32 is also configured to receive plug 38 having bluff surface 104. Fluid entering chamber 102 through inlet 106 is dispersed and redirected by plug 38 and into outlet 124 that terminates downstream at section 68 of second chamber 64. The fluid dispersion characteristics of transducer 32 can be seen in greater detail with reference to U.S. Pat. No. 4,972,830 and EP308524B, which are expressly incorporated by reference herein.

The fluid source 22 is biased to discharge along axis 86 by compressing a loading member, such as biasing spring 48, between the top cap 54 and container sleeve 46, which is adapted to receive the other end of the container 108 opposite the nozzle 110. Biasing spring 48 preloads the container 108 to move in the direction of surface 112 of transducer 32 along the discharge axis 86.

In the stowed configuration shown in FIG. 3A, the fluid source container 108 is retained from translating along axis 86 by a collapsible linkage comprising upper link 26 and lower link 28. Upper link 26 and lower link 28 are rotatably coupled at a collapsible knee-type joint 66. The upper end of upper link 26 has a pair of bosses 92 that are retained by a pair of guides 122 in the container holder 24 having slots 90. The guides are generally in-line, or at least parallel with the discharge axis 86, and allow motion of the bosses 92 (see FIG. 7A) of the upper link to slideably translate upward and downward in the discharge axis 86, as well as allow the boss to rotate as necessary. The lower link 28 has one end fixed to the transducer 32 at pivot 78. As illustrated in FIG. 3A, the boss 92 of the upper link 26 and pivot 78 of the lower link are essentially in-line with discharge axis 86, i.e. they form a loading path that is parallel to, or aligned with the discharge axis 86. Because collapsible joint 66 is off-center, i.e. positioned away from the loading path formed by the boss 92 of the upper link 26 and pivot 78, the downward force imposed by biasing spring 48 on the container 108 in the stowed position predisposes the knee joint 66 to collapse. Such collapse is restrained in the stowed position by imposition of arm 74 of lower link 28 on flap 34.

FIG. 3B illustrates the initiation of the breath actuation mechanism 100 caused by inhalation by a patient through the opening 60 of horn 58. As shown in FIGS. 3B-3C and 4A, an outward airflow 80 is created in the second chamber 64, which pulls through a plurality of slots 70 in the transducer. Suction of air through slots 70 creates a small pressure differential 82 across the inner surface of flap 34, causing the flap to rotate about peg 98 and into the cavity of the transducer 32, as illustrated in FIGS. 3A and 3B. The gap 76 between the flap 34 and the transducer 32 provides enough clearance to allow the flap to rotate into the cavity of the transducer, while also being small enough to allow a pressure differential with minimal suction on the horn. As the flap 34 rotates, arm 74 of the lower link 28 is no longer retained by the upper surface 72 of the flap, and the arm 74 clears the flap 34 through recess 88 as the lower link 28 is allowed to rotate about pivot 78.

With rotation of the lower link 28 as shown in FIG. 3C, the collapsible joint 66 moves over center, allowing the container holder 24 and container 108 to translate downward along axis 86, forcing a portion of the nozzle 110 into the container 108 to stimulate discharge of the medicament from the container 108. The medicament travels through the first chamber 102 and into the second chamber 64 where it is entrained with air flowing through slots 70, as described in further detail in U.S. Pat. No. 4,972,830, previously incorporated by reference. In the embodiment shown, the second chamber 64 has an internal cross section that is shaped like a parabola. The entrained medicament flows through the second chamber 64 and out of the opening 60 of horn 58 to be inhaled by the patient. Therefore, the release of the metered dose of medicament is timed to be inhaled by the patient at an optimal moment during the inhalation phase of the patient's breath cycle.

After the inhalation of the dose by the patient, the flap is returned to its nominal position shown in FIG. 3D by a return force exerted by flap spring 36. Flap spring 36 is a metallic rod or wire assembled between retention arms 96 of the transducer 32 and flange 94 on the flap 34. Rotation of the flap bends the spring to create a return force to return the flap 94 to its nominal position after the inhalation forces have subsided.

The upper and lower links 26, 28, container holder 24, and container 108 remain in the collapsed discharge position as seen in FIG. 3D due to the force imposed by the biasing spring 48. The return of the dust cover 40 (described in greater detail with reference to FIGS. 7A-7E below) to cover the horn 58 manually forces the container holder 24 and container 108 to return to the stowed position under compression from biasing spring 48. Return torsion spring 30 is mounted on lower link 28 to engage the transducer 32 such that a torsional force is exerted on the collapsible linkage to return to the locked configuration. The collapsible joint 66 is thus retained from collapsing once the dust cover 40 is again opened.

Turning to FIGS. 7A-7E, the operation of the dust cover 40 will now be described. In the present embodiment, the dust cover 40 not only serves as a shield to cover horn entrance 60, but it also serves to reset the container to the stowed position after discharge of the medicament. FIG. 7A illustrates inhaler 20 in a stowed configuration with the dust cover 40 shielding the entrance 60 to horn 58. The dust cover 40 is pivotably connected to the transducer 32 such that it can be rotated out of place to allow access to the horn opening 60. In alternative embodiments, the dust cover may be pivotably connected to either the front or back covers 42, 44. The dust cover 40 has two cams 120, which are configured to engage the bottom surface of guides 122 of container holder 24 through its entire range of motion along axis 86. When the dust cover 40 is rotated about pivot 118 (shown in FIG. 7B), the cams disengage guides 122. The container holder 24 and container 108 remain in the stowed position from the over-center orientation of the collapsible linkage.

FIG. 7C illustrates the breath actuation assembly 100 in the collapsed configuration with the container holder 24 and container 108 in the discharge position. The breath actuation assembly 100 is biased to remain in this configuration due to the compressive force of the biasing spring 48. When the dust cover is rotated back toward the horn opening 60, as shown in FIG. 7D, the cams 120 engage the bottom surface of guide 122, pushing the container holder 24 and container 108 upward along axis 86. When the dust cover 40 is in its final stowed position covering the horn entrance 60, the cams 120 have pushed the container holder 24 to the stowed position, as shown in FIG. 7A. In this configuration, the return spring 30 has reset the breath actuation assembly 100 to the locked position, and movement of the container 108 will be retained by the dust cover cams independent of the collapsible linkage.

The inhaler 20 preferably includes a dose counter for automatically counting the remaining doses left in the container after each discharge of the medicament. The inhaler may be configured with a dose counter having a number of different configurations, including mechanical or electrical counters. The operation of a preferred embodiment utilizing a mechanical dose counter assembly 130 will be described with respect to FIGS. 8A to 12E.

FIG. 8A illustrates inhaler 20 with dose counter assembly 130 configured above the container sleeve 46. The container sleeve 46 is sized to receive the non-dispensing end of the container 108. The container sleeve preferably has one or more tabs 132 having a boss 136 configured to engage the teeth of first wheel 50 disposed just above the container sleeve 46. The embodiment shown in FIG. 9 has two tabs 132 and bosses 136. However, it will be appreciated that any number of tabs and bosses may be employed.

Referring back to FIG. 8A, first wheel 50 is a gear rotatably mounted in a horizontal orientation to top cap 54. Wheel 50 has a plurality of lower teeth 140 and upper teeth 138 disposed along the outer perimeter of wheel 50.

In a preferred embodiment, display wheel 52 is also rotatably mounted to top cap 54 in a horizontal orientation between first wheel 50 and the top cap. Display wheel 52 has an opening 154 to allow clearance for column 142 of first wheel 50 that is vertically disposed to mount to top cap 54. Display wheel 52 has markings 150 to indicate the number of doses left in the container 108 based on the position of the display wheel 52. As seen in FIGS. 2A and 2B, the markings 150 that are showing through opening 56 in top cap 54 indicate the number of remaining doses.

FIGS. 8A-8D illustrate the interaction between the container sleeve 46 and the first wheel 50 upon discharge of the fluid source 22. When the container 108 is in the stowed position, boss 136 lines up on the perimeter of wheel 50 between two of the upper teeth 138. As the container 108 and container sleeve 46 moves downward along the discharge axis as a result of the breath actuation mechanism, boss 136 contacts the upper incline of one of the lower teeth 140, as shown in FIG. 8B. The boss 136 continues its translation along axis 86, forcing the first wheel 50 to turn clockwise (looking down from the top) until the container 108 reaches the discharge position, as shown in FIG. 8C. When the dust cover 40 is closed to return the container 108 to the stowed position, boss 136 translates upward until contacting the lower incline of upper tooth 138, as shown in FIG. 8D. The boss 136 continues its upward translation, forcing the wheel 50 to further turn clockwise until the container 108 reaches the stowed position, shown in FIG. 8A. When another dose is dispensed, the cycle repeats.

The lower wheel 50 may be configured to vary the number of doses required to turn the lower wheel 360 degrees by varying the number of teeth. In the above embodiment, a 40-tooth index was used. However, this number may be varied depending on the number of doses included in the container.

FIGS. 12A-12C illustrate the interaction between the display wheel 52 and the lower wheel 50. As shown in FIG. 10 and in hidden line in FIGS. 12A-12C, the lower wheel 50 has a drive peg 144 disposed on the upper surface of the lower wheel. Display wheel 52 has a plurality of semi-circular receiving pegs 152 disposed on the lower surface of the display wheel. As first wheel rotates about column mount 142, drive peg 144 engages a first of the receiving pegs 152 and causes the display wheel 52 to rotate about mount 156 a specified distance along mark 150, the specified distance indicating the range of doses left (e.g. “full 200 to 160”) (see FIG. 12A). At a portion of first wheel's rotation, the drive peg 144 slips past the first of the receiving pegs 152 (see FIG. 12B) and continues to complete one full rotation (40 doses) until contacting the second of the receiving pegs 152 (FIG. 12C). The cycle repeats itself until all the receiving pegs 152 are driven such that the “empty” indicator is displayed at window 56 when the specified number of doses has been dispensed.

The effect of the gearing as shown in FIGS. 12A-C is to scale the motion of the display wheel 52 with respect to the first wheel 50. To change the scale of the motion, one or more additional driving pegs 144 may be disposed on the upper surface of the first wheel 50. For example, a second driving peg (not shown) may be disposed 180 degrees from the first such that the display wheel would advances twice as fast relative to the first wheel for a container having 100 total doses.

FIG. 13 illustrates an alternative embodiment showing an inhaler having a breath actuated release mechanism 200 using a diaphragm 202 rather than the flap 34 shown in FIGS. 1-7E. The diaphragm 202 is configured to mount to transducer 204 and be sized so that a portion of the diaphragm deflects in response to inhalation forces from the patient. Release mechanism 200 further includes a catch 204 coupled to the diaphragm and the lower link 208 to retain the collapsible linkage comprised of the lower link 208 and the upper link 210.

During use, inhalation forces from the patient deflect the portion of the diaphragm in communication with catch 204. Motion of the catch 204 allows lower link 208 to rotate past the catch, thereby allowing the 208/210 linkage to collapse and discharge fluid source 22.

FIGS. 14-17 illustrate another alternative embodiment of inhaler 300 having a load lever 302 and a breath actuated release mechanism 350 on top of fluid source 22. By placing the release mechanism above the MDI container, the mechanism can be applied to any MDI actuator with minimal mold modification. Inhaler 300 has a lower portion 304 housing fluid source 22 and a transducer (not shown) for dispersing the medicament. Middle body 308 interfaces with lower portion 304 and slideably houses plunger 318 to selectively advance fluid source 22 downward to discharge the medicament.

Plunger 318 is retained from moving relative to middle body 308 by a collapsible linkage comprising lower link 320 and upper link 322. Plunger 308 is also configured to receive biasing spring 312 at its up extremity. The biasing spring 312 is shaped to receive spring cap 310 which may be depressed to compress spring 312 against plunger 318 in a downward discharge direction, as shown in FIG. 16A. To depress spring cap 310, load lever 302 is rotatably attached to top shell 306 such that rotation of load lever 302 to a vertical orientation forces the spring cap 310 down to bias the plunger to discharge fluid source 22.

Motion of the collapsible link 320, and linkage 320/322, is restrained by flap 316. Flap 16 is pivotably mounted such that inhalation forces cause it to rotate as illustrated in FIG. 16B, thereby allowing the lower link 320 to rotate downward such that linkage 320/322 collapses. The biasing force from spring 312 forces the plunger downward as illustrated in FIG. 16C. The load lever 302 is then reset to the first position, allowing the fluid source 22 to translate back to the stowed position illustrated in FIG. 16D.

FIG. 17 illustrates an embodiment of the inhaler 300 incorporating an electronic dose counter 324. In such a configuration, flap 316 is coupled to trigger 326, which depresses a sensor in dose counter 324 each time the flap is tripped to dispense a dose of medicament. Dose counter 324 generally comprises a printed circuit board (PCB) and other electronic components such as an LCD to digitally display the dose count. Alternatively, a mechanical dose counter may instead be incorporated into inhaler 300 in much the same way as the inhaler disclosed in FIGS. 9-12, or FIGS. 21A-23.

FIGS. 18 through 20B illustrate another alternative embodiment of the present invention with inhaler 400 having a mechanical dose counter 420 that has a vertically mounted display wheel 422. Inhaler 400 has a load lever 402 that manually biases the fluid source 22 discharge upon downward motion.

As illustrated in FIG. 19A, fluid source 22 is retained from discharging by collapsible joint 416, which is formed by the junction of upper link 406 and lower link 408. Lower link is coupled to horizontally oriented flap 410. Inhalation forces on horn 404 cause air flow through port 412 into negative pressure chamber 414 such that a negative pressure is exerted on flap 410 to force flap 410 to rotate downward, as shown in FIG. 19B. With collapsible joint 416 away from the locked position, the fluid source is free to translate downward and discharge the medicament.

FIGS. 20A and 20B illustrate an alternative embodiment of using a dose counter 420 with a vertically oriented display wheel 422. Container sleeve 426, adapted to receive the non-dispending end of container 22, has a plurality of protrusions 434. When the container cycles downward upon discharge, translation of the container sleeve 426 causes protrusions 434 to strike the teeth 432 of gear 424, forcing the gear 424 to rotate clockwise. The clockwise rotation of gear 424 engages vertically oriented sprocket 430 of display wheel 422, causing the display wheel 422 to turn. Sprocket 430 may be configured to engage gear 424 at specified intervals to vary the rate of rotation of the display wheel 422 with respect to the rate of rotation of the gear 424.

Referring now to FIG. 21A-F, another preferred embodiment is shown as dose counter mechanism 450. In FIG. 21A, the mechanism 450 is in ready state (prior to breath actuation) with the canister sleeve 46 in the upward-most position in its travel. The canister sleeve 46 has a plurality of teeth 456 that are shaped to mate with and lock with the teeth 454 of a rotational member, or top link 452. I.e., both teeth 456 and 454 have opposing angled surfaces that shift the angular position of the top link 452 with the canister sleeve 46 when engaged. When MDI canister 22 (shown in FIG. 1B) is actuated, the canister sleeve 46 and top link 452 move downward.

A compression load is generated on the top link 452 from count spring 462, which is disposed between the display wheel 464 and top link 452. The top link has a plurality of radial protrusions, or keys 460 which are positioned and sized to mate with the columnar tines 458 of cap bottom 466. Cap bottom 466 may be bonded to or integral with top cap 470 (shown in FIG. 22), such that the cap bottom 58 remains fixed during motion of the canister sleeve 46. Because of the compression force applied by the count spring 462, the opposing inclined surfaces of the key 460 and cap bottom 466 cause the top link 452 to lift from the canister sleeve 46 and rotate 4.5°, sliding on the opposing angled surfaces as seen in FIG. 21B. The top link is coupled to gear column 468 a such that gear column 468 rotates incrementally with rotation of the top link 452

Referring now to FIG. 21C, the canister sleeve 46 continues to travel downward, following the keys 460 of the top link to push in between the columnar tines 458 of the cap bottom 466. When the canister sleeve 46 has bottomed out, as shown in FIG. 21D, it will then rebound and then start moving up toward its original ready state position, pushing the top link 460 up with it. As the canister sleeve 46 moves up, the key 460 clears the tines 458 of the cap bottom 466 as shown in FIG. 21E. The teeth 456 of the canister sleeve 46 then re-engage the teeth 454 of the top link 452, causing the top link 452 to rotate another 4.5° clockwise, as shown in FIG. 21 F. This completes the full cycle of MDI canister actuation and the indexing mechanism rotated a total of 9°. The indexing mechanism top link 452 has advanced 1/40th of a full revolution per actuation.

Referring now to FIG. 22A, the dose counter mechanism 450 is mounted on top of the breath actuation assembly 100 (see FIG. 1B). Top cap 470 surrounds canister sleeve 46, shown in FIG. 22B with a section of the top cap 470 removed for clarity. The top cap has a window 472 for showing the dose count as provided by the display wheel 464. Display wheel 464 has a display label 474 showing remaining dose counts from 0 to 200 in ten dose increments (e.g. markings of 200, 190, 180, etc.)

FIG. 23 illustrates a top portion of the top cap 470 cut out and display label 474 removed to show planetary gear mechanism 478. The display wheel 464 is rotationally coupled to gear column 468 via three intermediary gears 476. The three intermediary gears 476 of the planetary gear mechanism 478 are driven by the rotation of center gear column 468. The teeth of the three intermediary gears 476 mate with the internal geared surface of the top cap 470 such that the display wheel 464 rotates clockwise. When the center gear column 468 rotates 9° due to motion of the indexing mechanism, the planetary gear will rotate the display wheel 1/10 of a graduation. The label is set to a resolution of 10 shots per indication, however may be altered to reflect different increments. After 200 actuations, the label will have advanced total of 260°—going from “200” to “0” or “Empty”.

The planetary gear mechanism 478 has the effect of scaling down the rotational motion of the top link 452 and gear column so that the display wheel may rotate through 200 actuations in less than one full rotation. For smaller dose counts (e.g. 120 or 60 count canisters), the display wheel may simply be positioned so that the correct count is initially viewed through window 472. Alternatively, a different tooth count for the planetary gear mechanism 478 may be implemented along with changing the display label 474 to accommodate different total dose counts.

Referring to FIG. 24A-D, the breath actuation mechanism 500 is another preferred embodiment that incorporates a trip link 502 to increase the operational range of previously described breath actuation mechanism 100 shown in FIGS. 3A through 4E.

FIG. 24 illustrates the breath actuation mechanism in ready (non actuated, and loaded) state. Instead of interfacing directly with flap 34, lower link 504 interfaces indirectly with flap 34 via trip link 502. The upper link 506 and lower link 504 retain motion of the fluid source 22 and load F from biasing spring via locking knee joint 66. Knee joint 66 is located off-center from load F in discharge axis 86 (i.e. the discharge axis 86 passes through pivot 78 and the boss 516 of upper link 506 throughout FIGS. 24A-D), thus the downward force imposed by biasing spring 48 on the container 108 in the ready position predisposes the knee joint 66 to collapse.

The upper link 506 and lower link 504 are restrained from rotating or collapsing because the lower link 504 is locked from rotation from a catch, or trip edge 510 in trip link 502. Trip link 502 is locked from rotating because of impingement of upper surface (contact surface) 512 of the trip link 502 with a restraining surface, or circular cutout 514, in flap 508.

Referring now to FIG. 24B, when flap 508 rotates due to the force created by patent inhalation (vacuum), upper edge 512 if the trip link clears the cutout 514, allowing the trip link 502 to rotate to rotate clockwise. Trip edge 510 correspondingly rotates to release the contacting surface of the lower link 504.

With lower link 504 now unrestrained, as shown in FIG. 24C, knee joint 66 collapses and shifts to the left. Because of constraints on the top edges of upper link 506 with container holder 24, the upper link can only travel in line with the force load path F, and trip link 502 further rotates clockwise, causing lower link 504 to further rotate counter clockwise.

Referring now to FIG. 24D, the mechanism further collapses as lower link 504 continues to rotate counter-clockwise on joint 78, 26 travels down allowing the MDI canister 22 to travel downward causing the valve stem to activate.

After the activation, the canister travels upward such that the knee joint moves back toward its stowed orientation with lower link rotating clockwise toward trip link 502. The trip link 502 is able to catch lower link 504 in trip edge 510 for retention of the knee joint 66 until subsequent breath actuation of flap 508.

The addition of trip link 502 over previously described embodiments expands the operational margin of the lower 504 with the flap 508, improving overlap on trip edges to ease manufacturing tolerances while maintaining breath actuation sensitivity.

Although the description above contains many details, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. Therefore, it will be appreciated that the scope of the present invention fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the present invention is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” All structural, chemical, and functional equivalents to the elements of the above-described preferred embodiment that are known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Moreover, it is not necessary for a device or method to address each and every problem sought to be solved by the present invention, for it to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. 112, sixth paragraph, unless the element is expressly recited using the phrase “means for.” 

1. An apparatus for dispensing a fluid supplied from an external fluid source, comprising: a housing adapted for receiving the fluid from the fluid source, wherein translation of a portion of the fluid source from a stowed position to a discharge position along a first axis releases the fluid into the housing; a loading member coupled to the fluid source, the loading member imposing a biasing force on the fluid source in the stowed position to discharge the fluid source along the first axis; and a linkage coupling the housing and the fluid source, the linkage having a collapsible joint; the collapsible joint connecting first and second links configured to restrain translation of the fluid source in the first axis; the second link having a first end pivotably mounted to the housing, a second end pivotably connected to the first link at the collapsible joint, and an arm coupled to a restraining surface on a movable member; the moveable member responsive to an inhalation force, the inhalation force causing the movable member to shift the restraining surface to release the collapsible joint, thereby allowing translation of the fluid source in the first axis from the stowed position to the discharge position to discharge the fluid into the housing.
 2. An apparatus as recited in claim 1, wherein the moveable member comprises a flap rotatably mounted to the housing, wherein the flap rotates in response to the inhalation force to shift the restraining surface.
 3. An apparatus as recited in claim 2: wherein the arm of the second member is restrained by a trip link; the trip link rotationally coupled to the flap; the trip link having a catch restraining motion of the arm of the second link in the stowed position.
 4. An apparatus as recited in claim 3: wherein the first link has a first end rotationally and slideably mounted to the container, such that the first end of the first link is allowed to translate in the discharge axis; wherein the first ends of the first and second links lie in a loading path parallel to the first axis; and wherein the collapsible joint is located off-center from the loading path in the stowed position such that the collapsible joint is predisposed to collapse in absence of restraint from the moveable member.
 5. An apparatus as recited in claim 4, further comprising: a holder configured to receive a first end of the fluid source; and wherein the holder allows translation of the first end of the first link along the loading path to allow collapse of the collapsible joint when not restrained by the moveable member.
 6. An apparatus as recited in claim 5: wherein the container holder further comprises one or more protrusions; the apparatus further comprising a dust cover pivotably coupled to the housing; and wherein the dust cover comprises one or more cams, the one or more cams configured to contact the one or more protrusions on the holder upon rotation of the dust cover to advance the holder and linkage from the discharge position to the stowed position.
 7. An apparatus as recited in claim 6, wherein the trip link is configured to engage the arm of the second link upon advancement of the holder from the discharge position to the stowed position.
 8. An apparatus as recited in claim 3: wherein the trip link has a contact surface mating with the restraining surface of said flap; wherein said restraining surface is configured to inhibit rotation of the trip link with respect to the flap when the flap is in a first orientation to retain the arm of the second link in the catch; and wherein the flap is configured to rotate from a first orientation to a second orientation to allow the contact surface of the trip link to advance past the restraining surface of the flap, thereby allowing the trip link to rotate to release the arm of the second link from the catch.
 9. An inhaler for dispensing metered doses of a medicament, comprising: a housing having a surface configured to engage a nozzle of a fluid source, the surface adapted for receiving a medicament contained in the fluid source; the fluid source comprising a container having the nozzle located in line with a discharge axis of the container, wherein the nozzle discharges the medicament after the container is advanced relative to the nozzle from a stowed position to a discharge position along the discharge axis; a loading member coupled to the container, the loading member imposing a biasing force to the container in the stowed position to discharge the container along the discharge axis; and a linkage coupling the housing and the container, the linkage having a collapsible joint; the collapsible joint connecting first and second links configured to restrain translation of the container in the discharge axis; wherein the first link comprises a first end slideably coupled to the container such that the first end of the first link is free to translate in the discharge axis; wherein the second link comprises a first end pivotably mounted to the housing such that the first end of the first link is restrained from translation with respect to the housing; wherein a second end of the first link is pivotably attached to a second end of the second link to form the collapsible joint; wherein the collapsible joint is restrained from moving by a restraining surface on a movable member; and wherein the moveable member is responsive to an inhalation force, the inhalation force causing the movable member to shift the restraining surface to release the collapsible joint, thereby allowing translation of the container in the discharge axis from the stowed position to the discharge position to discharge the fluid into the housing.
 10. An inhaler as recited in claim 9: wherein the first ends of the first and second links lie in a loading path parallel to the discharge axis; and wherein the collapsible joint is located off-center from the loading path in the stowed position such that the collapsible joint is predisposed to collapse in absence of restraint from the moveable member.
 11. An inhaler as recited in claim 10: wherein the moveable member comprises a flap rotatably mounted to the housing; and wherein the flap rotates in response to the inhalation force to shift the restraining surface.
 12. An inhaler as recited in claim 11: wherein the second link has an arm restrained by the restraining surface of the flap; and wherein the flap is configured to rotate from a first orientation retaining the arm of the second link, to a second orientation releasing the second link from the restraining surface, thereby collapsing the collapsible joint as a result of the force applied in the discharge axis.
 13. An inhaler as recited in claim 12, further comprising: a trip link disposed between the flap and the arm of the second link; wherein the arm of the second link is restrained by the trip link in the stowed position; wherein the trip link is rotationally coupled to the flap; the trip link having a catch configured to retain a free end of the arm of the second link in the stowed position.
 14. An inhaler as recited in claim 13: wherein the trip link has a contact surface mating with the restraining surface of said flap; wherein said restraining surface is configured to inhibit rotation of the trip link with respect to the flap when the flap is in a first orientation to retain the free end of the second link in the catch; and wherein the flap is configured to rotate from the first orientation to a second orientation to allow the contact surface of the trip link to advance past the restraining surface of the flap, thereby allowing the trip link to rotate to release the free end of the arm of the second link from the catch.
 15. An inhaler as recited in claim 10, further comprising: a container holder configured to receive a first end of the container; wherein the container holder allows translation of the first end of the first link along the loading path to allow collapse of the collapsible joint when not restrained by the moveable member.
 16. An inhaler as recited in claim 15: wherein the container holder further comprises one or more protrusions; the apparatus further comprising a dust cover pivotably coupled to the housing; and wherein the dust cover comprises one or more cams, the one or more cams configured to contact the one or more protrusions on the container holder upon rotation of the dust cover to advance the container holder and linkage from the discharge position to the stowed position.
 17. An inhaler as recited in claim 16, wherein the trip link is configured to engage the free end of the second link upon advancement of the container holder from the discharge position to the stowed position.
 18. An inhaler for dispensing metered doses of a medicament; comprising: a fluid source containing the medicament, the fluid source configured to discharge the medicament upon translation of a portion of the fluid source from a stowed position to a discharge position along a discharge axis of the fluid source, the portion of the fluid source configured to translate back along the discharge axis to recharge the medicament; a housing configured to house the translating portion of the fluid source; first and second, third and fourth angled contact surfaces coupled to the housing; a rotational member coupled to the housing such that the rotational member translates in the direction of the housing in the discharge axis; the first angled surface being disposed on the rotational member in opposition to the second angled surface; the third angled surface being disposed on the rotational member in opposition to the fourth angled surface; and a display wheel coupled to the rotating member; wherein the first and second opposing angled surfaces are configured such that motion of the housing upon discharge engages the first and second opposing angled surfaces to rotationally advance the rotation member with respect to the housing; wherein the fourth angled surface is fixed from rotational motion such that motion of the housing upon recharge engages the third and fourth opposing angled surfaces, thereby further rotating the rotation member with respect to the housing; wherein the display wheel is configured to advance in response to motion from the rotation member to indicate the number of metered doses dispensed from the fluid source.
 19. An inhaler as recited in claim 18, wherein motion of the display wheel is scaled with respect to the motion of the rotation member.
 20. An inhaler as recited in claim 19, further comprising: a planetary gear mechanism coupling the rotational member; the planetary gear mechanism scaling motion of the display wheel to be a fraction of the motion of the rotational member.
 21. An inhaler as recited in claim 18, wherein the first angled surface comprises one or more keys disposed on a perimeter of the rotating member.
 22. An inhaler as recited in claim 21, wherein the second angled surface comprises a plurality of tines disposed on the inside of a cover disposed around the housing; the one or more keys configured to engage successive tines upon each discharge of the fluid source.
 23. An inhaler as recited in claim 18, wherein the rotational member is biased to move in direction of housing by imposition of a spring between the housing and the rotational member. 